Evaluation of exosomes encapsulated recombinant Interleukin-29 for its in vitro anticancer studies

Exosomes have recently been considered ideal biotherapeutic nanocarriers that broaden the frontiers of current drug delivery systems to overcome the shortcomings associated with cytokine-based immunotherapy. Using this approach, the current study aimed to assess anti-proliferative activity of purified IL-29 and exosomes encapsulated IL-29. The IL-29+pET-28a construct was transformed into Rosetta 2(DE3) cells which was used for the large-scale production of IL-29. Exosomes isolated from H1HeLa, and SF-767 cells using Total Exosome Isolation reagent were loaded with IL-29 via sonication. Isolation of exosomes was validated using their core protein signature by western blotting and specific miRNA profiles by RT-PCR. The drug loading efficiency of exosomes derived from H1HeLa cells was higher than that of SF-767-derived exosomes. The drug release kinetics of IL-29 encapsulated exosomes exhibited stable release of the recombinant drug. Around 50% of all cancer cell lines survived when IL-29 was administered at a concentration of 20 µg/mL. A survival rate of less than 10% was observed when cells were treated with 20 µg/mL IL-29 loaded exosomes. It was concluded that IL-29 loaded exosomes had a more significant cytotoxic effect against cancer cells, which might be attributed to sustained drug release, improved half-life, superior targeting efficacy, capacity to harness endogenous intracellular trafficking pathways, and heightened biocompatibility of exosomes.

Large-scale purification and characterization of recombinant human stem cell factor in Escherichia coli

The pharmacological importance of recombinant human stem cell factor (rhSCF) has increased the demand to establish effective and large-scale production and purification processes. A good source of bioactive recombinant protein with capability of being scaled-up without losing activity has always been a challenge. The objectives of the study were the rapid and efficient pilot-scale expression and purification of rhSCF. The gene encoding stem cell factor (SCF) was cloned into pBV220 and transformed into Escherichia coli. The recombinant SCF was expressed and isolated using a procedure consisting of isolation of inclusion bodies (IBs), denaturation, and refolding followed by chromatographic steps toward purification. The yield of rhSCF reached 835.6 g/20 L, and the expression levels of rhSCF were about 33.9% of the total E. coli protein content. rhSCF was purified by isolation of IBs, denaturation, and refolding, followed by SP-Sepharose chromatography, Source 30 reversed-phase chromatography, and Q-Sepharose chromatography. This procedure was developed to isolate 5.5 g of rhSCF (99.5% purity) with specific activity at 0.96 × 10⁶  IU/mg, endotoxin levels of pyrogen at 1.0 EU/mg, and bacterial DNA at 10 ng/mg. Pilot-scale fermentations and purifications were set up for the production of rhSCF that can be upscaled for industry.

Optimization of conditions for high-level expression and purification of human recombinant consensus interferon (rh-cIFN) and its characterization

Recombinant human consensus interferon (rh-cIFN) is an artificially engineered interferon (IFN) developed by recombining and reordering the protein sequences that exist in standard IFN. This recombination resulted into a drug that has the potential to work better than natural, standard IFN. In this study, we described optimized conditions for high-level expression and recovery of biologically active consensus IFN from inclusion bodies (IBs). A synthetic gene coding 166 amino acids of consensus IFN was cloned under the T7 promoter. Escherichia coli strain BL21DE3Plys was used to transform expression construct. For high-level expression, shake-flask fermentation conditions were standardized. For isolation of IBs, the sonication method was optimized. A variety of chaotropic agents including guanidine hydrochloride, urea, SDS, and detergents were studied for solubilization of IBs. For renaturation of solubilized denatured protein by the dilution process, parameters of dilution factor, temperature, and l-arginine were optimized. A one-step chromatography method was developed for high-yield purification of consensus IFN. rh-cIFN was characterized by SDS-PAGE, Western blot, and high-performance liquid chromatography. Purified protein has a molecular weight of 19.5 kDa and specific activity was 2.0 × 10(8) as determined by the cytopathic inhibition assay. This study concludes that by using optimized conditions, we obtained a yield of 100 mg/L of biologically active rh-cIFN, which is highest ever reported according to available data.